1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method of the same, and more particularly, it relates to an improvement of an interconnection structure in the semiconductor device.
2. Description of the Prior Art
A semiconductor device having a multi-layer structure of conductive layers in which some conductive layers are connected to each other is well-known in the art in its characters of a high data processing speed and a high degree of integration. A conventional multi-layer structure of conductive layers is disclosed in "A VLSI Bipolar Metallization with Three-Level Wiring and Area Array Solder Connections", IBM J. RES DEVELOP. VOL. 26 No.3, pp 362-371, May 1982, for example.
A part of a conventional semiconductor device having such a multi-layer structure of conductive layers is shown in FIG. 1A and FIG. 1B, where FIG. 1A is a plane view and FIG. 1B is a sectional view taken along a line X-Y in FIG. 1A. On one major surface of a semiconductor substrate 101, an insulating layer 102, an conductive layer 103 and an insulating layer 104 are serially provided. A conductive layer 105 is selectively formed on the upper surface of the insulating layer 104, and an insulating layer 106 having a window covers the exposed surfaces of the insulating layer 104 and the conductive layer 105. The window is served as a contact hole 106 through which a conductive layer 108, which is selectively given on the insulating layer 106, contacts with the conductive layer 105. On the exposed surfaces of the insulating layer 106 and the conductive layer 108, an insulating layer 109 is formed. Respective one of-the conductive layers 103, 105 and 108 may be formed as a double-layer such as a policide film or a multi-layer having more than two layers. A contact hole 107 is shaped through the insulating layer 106 at a position between the conductive layers 105 and 108, through which the conductive layers 105 and 108 are electrically connected to each other. Another contact hole 110 is shaped through the insulating layers 104, 106 and 109, and a conductive layer 111 is formed on the insulating layer 109 to contact with the conductive layer 103 through the contact hole 110.
The conductive layers 103, 105, 108 and 111 are connected to internal circuits (not shown) provided in the semiconductor device, respectively. The internal circuits are connected to each other by the interconnection structure shown in FIG. 1A and FIG. 1B, according to the connection rule previously decided. For example, the respective internal circuits connected to the conductive layers 108 and 105 are electrically connected through the contact hole 107, while those connected to the conductive layers 111 and 103 are connected through the contact hole 110.
Although the conventional interconnection structure is suitable for a single interconnection, it has a disadvantage that a plurality of contact holes must be provided in the case that two or more interconnections are required. For example, two contact holes 107 and 110 must be formed for obtaining two interconnections, one of which is the interconnection between the conductive layers 105 and 108, and the other is between the conductive layers 103 and 111. Namely, the number of contact holes increases in proportial to the number of interconnections, and increased number of the contact holes brings a complex process on the manufacture of the semiconductor device. As a result, it is difficult to improve the yield of the semiconductor device.
Further, since the contact holes must be formed respectively at different positions above the substrate a rate of the occupation area of contact holes to the whole surface area of the substrate is relatively large, thereby a layout of elements on the substrate is complicated.
Moreover, when an interconnection between the lowest conductive layer 103 and a conductive layer (not shown) provided on the insulating layer 109 is required, a multi-layer structure consisting of the insulating layers 104, 106 and 109 through which the contact hole is shaped must be formed on the substrate.